1. Field of the Invention
The present invention relates to user authentication techniques and, in particular, to techniques for validating input by detecting and recognizing human presence.
2. Description of the Related Art
Handheld devices, such as mobile phones, have evolved to provide sophisticated computing platforms, complete with large display areas, touch-sensitive surfaces, among other components. Further, the computing power of these devices has steadily increased, allowing sophisticated computing applications to be executed from the palm of one's hand. Recently, handheld devices have been introduced which include sensors which can acquire physical data about the devices' position, orientation, motion, and surrounding environment, among other things. For example, accelerometers and gyroscopes on handheld devices may allow applications to sense and respond to changes in acceleration and spatial orientation as the devices are tilted in different axes.
Applications running on handheld devices may receive inputs which need to be validated as human inputs. For example, applications may validate login credentials as user-entered so as to prevent automated scripts from accessing a given service, attempting to guess username/password combinations, and the like. One approach for validating input as human input uses CAPTCHA challenges which typically present images of distorted text. Humans are typically better than computer programs at reading such distorted text.